This invention relates generally to position sensors and more particularly to a position sensor for a microactuator in a mass storage device.
Mass storage devices such as hard disk drive systems generally include a magnetic storage media for storing information, a spindle motor for rotating the storage media, a magnetic read/write head for reading information from or writing information to the magnetic storage media, and an actuator for positioning the read/write head over the storage media. A control system associated with the actuator controls the movement of the actuator.
The read/write head is often positioned on an arm. This arm is positioned using the actuator mentioned above. However, such a system only provides coarse positioning of the read/write head. In order to further increase the data storage capacity of hard disk drives, the size of each data bit is constantly being reduced. The reduced data bit size requires increased accuracy in the positioning of the read/write head over the storage media. In order to provide finer adjustment of the position of the read/write head, microactuators are used that are positioned on an extreme end of the arm, where the read/write head is positioned.
The positioning force created by the microactuator can take many forms. For example, past actuator designs have used electrostatic, ferromagnetic, and piezoresistive actuation. An example system is described in xe2x80x9cDesign and Feedback Control of Electrostatic Actuators for Magnetic Disk Drivesxe2x80x9d by David A. Horsley, et. al. This paper was published at the Solid-State Sensor and Actuator Workshop, Jun. 8-11, 1998.
A problem that arises from the use of such a microactuators is determining the precise location of the read/write head in response to positioning by the microactuator. Position sensors or xe2x80x9cpick-offsxe2x80x9d are used for this purpose.
In addition to hard disk drives, there are numerous other applications that require precise positioning information.
Accordingly, a need has arisen for an apparatus for determining the precise position of a device, and more specifically, a read/write head in a hard disk drive. The present invention provides such a system and method for determining the position of a device.
According to one embodiment of the invention, a position sensor includes a stationary platform and a moveable platform. The position sensor further includes at least one beam coupling the moveable platform to the stationary platform. The at least one beam includes piezoresistive material that is positioned to provide an indication of a movement of the moveable platform relative to the stationary platform.
According to another embodiment of the invention, a hard disk drive system includes a disk storage media for storing information. The hard disk drive system also includes an arm operable to move over the disk storage media and an actuation system for positioning the arm relative to the disk storage media. Furthermore, the hard disk drive system includes a stationary platform coupled to an end of the arm and a head coupled to the stationary platform by a pair of beams. The head is used for recording and reproducing data in the disk storage media. A microactuator is used for positioning the head relative to the stationary platform, and piezoresistive material is positioned on the pair of beams to provide an indication of this movement of the head.
Embodiments of the present provide numerous technical advantages. For example, in one embodiment of the invention, a position sensor incorporates piezoresistive material to determine the precise location of a read/write head in a hard disk drive. Such precise location information allows for very fine adjustments in the position of the read/write head. In turn, this allows for storage of data on a hard disk drive at greater densities.